Association between Baseline NIHSS Limb Motor Score and Functional Recovery after Stroke: Analysis Based on a Multicountry Dataset

Abstract

Introduction: Motor skills are the domains most often affected by stroke, but a comprehensive assessment of motor function is often impractical in the acute setting. It could be useful to have a brief simple tool allowing the stratification of patients at the time of inclusion in clinical studies. Hence, our primary objective was to evaluate whether the baseline NIH Stroke Scale limb motor score (b-NIHSS-LMS), obtained by summing the four motor items 5a to 6b of the NIHSS, is associated with functional recovery assessed by the modified Rankin Score (mRS). A secondary objective was to apply this new tool in the context of a clinical trial. Methods: The analysed population considered for this research included subjects from a large published, double-blind, multicentre trial, randomised to receive either a combination of various herbal and non-herbal components (MLC601) or placebo, administered within 72 h after an acute ischaemic stroke of intermediate severity (defined by baseline NIH Stroke Scale [b-NIHSS] score of 8–14). Associations between b-NIHSS-LMS and favourable outcome, i.e., mRS 0–1 at month 3, were evaluated using logistic regression adjusted for baseline covariates and study treatment. Results: The analysis included 533 subjects with an acute ischaemic stroke of intermediate severity assessed at month 3. Analyses showed that b-NIHSS-LMS was independently associated with a favourable outcome (OR 0.84; 95% confidence interval 0.76–0.92; p < 0.0003) at 3 months. Furthermore, in the clinical study considered, a selection of patients based upon a sufficient level of motor impairment at study entry (b-NIHSS-LMS ≥3) would result in the detection of a more pronounced and longer-lasting treatment effect. Indeed, ORs of treatment effect versus placebo in the selected subgroup (b-NIHSS-LMS ≥3) were statistically significant from months 3–24. Discussion/Conclusions: As an independent association between b-NIHSS-LMS and functional recovery after an acute ischaemic stroke of intermediate severity was established in this study, we suggest that the b-NIHSS-LMS can be used as a stratification factor in large clinical trials to define a target population with poststroke motor impairments.